Through random screening, Ho Chi Minh City discovered 64% of samples positive for Omicron were the BA.2 variant – the so-called “stealth” variant.
According to information from Director of Ho Chi Minh City Department of Health Tang Chi Thuong morning 9/3, last week in the world, the number of new cases decreased by 4% and the number of deaths decreased by 19%.
In Southeast Asia, Vietnam emerged with a higher number of new infections than many countries. The question is why the number of cases increased so much and after Omicron, is there a new wave of Covid-19?
Mr. Thuong said the world experienced 3 waves and each wave corresponds to a mutation. Specifically, wave 2 is Delta and wave 3 is Omicron with 2 variants BA.1 and BA.2. Some countries experienced the 3rd epidemic, mainly BA.1, the BA.2 strain has only appeared in a few countries in Africa, India.
“BA.2 is the same as BA.1 in terms of disease transmission, but it spreads faster,” he said.
Thus, if there is a new wave BA. 2, is the vaccine still effective? The World Health Organization (WHO) has confirmed that vaccines are still effective in protecting the body from serious illness, but not enough to fight off infection. Therefore, Mr. Thuong affirmed that the vaccination campaign still has to be promoted.
In Ho Chi Minh City, as of this morning, through rapid screening by random sampling of 119 cases, 103 samples were found positive for Omicron.
However, this rapid screening technique only shows Omicron or not, and detailed Omicron BA.1 or BA.2 requires gene sequencing.
Through gene decoding of 67 cases, the city discovered 24 samples infected with BA.1 and 43 samples infected with BA.2, ie BA.2 accounting for 64%.
“Ho Chi Minh City currently has both strains and BA.2 is dominant, so that explains why it’s spreading so quickly. Regarding the subjective argument, we wouldn’t be too worried about a new strain because it’s already happening. If there is, then there is a different strain, and the world is preparing for the wave of BA.2”, said the Director of the Department of Health.
Two weeks earlier, the Director of the Ho Chi Minh City Department of Health once said that the Omicron strain had prevailed in Ho Chi Minh City. Specifically, the results of random screening of the Omicron variant by PCR test in the city from February 10 to 17, 70/92 samples showed positive results for the Omicron variant, accounting for 76%; Delta variation is only about 24%. This partly explains the increasing number of Covid-19 patients in the area due to the rapid infection rate of the new strain.
BA.2 is a sub-variant of Omicron. Some scientists give BA.2 the nickname “stealth Omicron variant”. This does not mean that the virus is not detected, but it is difficult to classify.
The original Omicron variant had specific genetic properties. It has a gene loss in the spike protein that results in what is known as an “S gene target error or S gene bypass” that allows medical personnel to quickly distinguish it from Delta using PCR testing. But BA.2 doesn’t have those genetic traits. Therefore, in tests it becomes more difficult to detect and classify as a sub-variant of Omicron, not to mention, very difficult to distinguish it from Delta.
@ Zing News